Menstruation or period occurs in humans and other animals when the unfertilized ovum is expelled at the end of the menstrual cycle. This happens in the so-called ‘luteal phase’.
The menstrual cycle consists of a set of cyclic processes and changes in the female reproductive system that make pregnancy possible.
Menstrual pain or dysmenorrhea is a problem associated with menstruation. It affects many women and may sometimes require treatment with analgesic medications.